Stationary contact structure



Feb. 23, 1943. M, scofi, JR 2,311,701

STATIONARY CONTACT STRUCTURE Filed June 10, 1940 3 Sheets-Sheet l Feb. 23,1943. w sco JR 2,311,701

I STATIONARY CONTACT STRUCTURE Filed June 10, 1940 3 Sheets-Sheet 2 b 1 5 -"Z.? J

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FIG.2. INVENTOR.

ATTORNEY v tion of each of the Patented Feb. 23, 1943 OFFICE STATIONARY CONTACT STRUCTURE William Maxwell Scott, Jr.,

signor to I. T. E.

Bryn Mawr, Pa., as-

Circnit Breaker Company,

Philadelphia, Pa., a corporation of Pennsylvania Application June 10, 1940, Serial No. 339, 688 8 Claims. (01. 200-147) This invention relates to circuit breakers and more particularly to the stationary contact structure thereof including the main stationary contact, the stationary arcing contact and arcing horn and the blow out coil connections thereof.

An important object of the present invention is to so arrange a magnetic blow out coil and magnetizable blow out plates in proximity to the position of the arc and'to the arcing horns so that the magnetic fluxes generated by the magnetic blow out coil as well as by the current of the arc itself may cause the arc to move in a predetermined position.

fin the operation and use of circuit breakers and switch gear of various types, it often becomes important to disassemble the same or at least to remove parts thereof-in order to obtain access to various portions of the circuit breaker for replacement or repair. I have attempted in the present invention to so arrange each of the parts thatvthey may be readily removable without any complicated operations whatever.

Thus the entire arc quencher assemblyincluding the magnetic pole pieces of the blow out coil may be removed after rotating a single screw. The entire contact assembly may be removed after having simply removed the two outerbearings of the contact shaft and the single pin connecting the contact shaft with the operating mechanism and removing the flexible conductors from'the lower terminal. And even here the link between the operating mechanism and the contact shaft is hinged sumciently to permit the entire contact assembly to be rotated outwardl to permit inspection and repair thereof.

An important object, therefore, of the present invention is the arrangement and integration of the parts thereof in such a manner asto facilitate assembly and disassembly thereof in manu facture, operation, replacement and repair.

In accordance with the necessity for integraparts and the construction thereof to permit ready removal and replacement thereof, the main stationary contact in the present invention comprises a member suitably;

shaped to be secured to 'a back connection stud which extend through the panel.

Furthermore, in order to secure such benefits which facilitate the arcing horn may also each be readily secured to the front of the panel. For this purpose, 'it is an important object of this invention to so arrange the main stationary contact and to so form the same that it may readily be secured'to the panel and to the back connection stud from the fmont of the panel by a simple-manual operaton. t

It is a further important object of the invention assembly and replacement, the' blow out coil, the stationary arcing contact and arrange the main stationary contact of the blow direction away from its original I out coil and the arcing contacts that they may each be readily secured to the front of the panel and by the securement be connected in appropriate relation to each other.

There are'many other objects and uses of the present invention and of the combinations and elements herein set forth. Many ofthem have already been pointed out. Many others will in part be apparent and where not intrinsically apparent will be pointed out in the following description and drawings, in which:

Figure 1 is a side elevation of the circuit breaker of my invention.

Figure 2 is a front view of the circuit breaker arrangement of Figure 1.

Figure 3 is a cross-sectional view on line 3-3 of Figure 2 showing the circuit breaker in closed circuit position.

Figurev 4 is a view corresponding to that of Figure 3 showing the circuit breaker in open circuit position.

Figure ifs a cross-sectional view on line 5-5 of Figure 4 showing the arrangement of the arc quencher.

Main supporting members The main bracket or housing 24 which supports the operating members is secured to the panel 23 by means of screws 25, 25 the heads of which are recessed in openings 26, 28 in the back of the panel 23 and which pass through the perforations 21, 21 in said panel toengage the main bracket 24 (Figure 1).. r

As seen in Figures 1 and 2, the main bracket or houjsing preferably comprises two flanged side plates 28 and 29 which extend on each side of a horizontal shelf 30 to which they are welded. V

The operating mechanism 3| comprising the toggles and other elements hereinafter described is bolted to the lower side of the shelf 30, the

shaft 45 and is rotatable therewith. As seen more particularly in Figures 3 and 4, the stationary contacts 36 and their back connection stud assembly are mounted on the panel abovethe housing or supporting bracket 24 and support the inner end of the arc chutes in the manner hereinafter described.

A bridge3'l of insulating material secured to the outer end of the main bracket 24 supports the outer end of the arc chutes in the manner hereinafter described.

Main andarcing contacts The stationary main contacts The stationary main contacts 36 are bolted to the connecting stud 42 by means of the bolts 38 and the washers 33. The connecting stud 42 passes through the back panel 23 and is suitably arranged so that appropriate circuit connections may be made thereto. The path of the main cur-= rent when the contacts are closed, as seen in Figure 3, is through the connection stud 42, the stationary contact 36, the stationary contact tip 46, the movable contact tip 4|, the contact lever 66 carrying the flexible connection 43 which in turn is electrically connected to the member.

Movable contacts support shaft. The contact arm 46 is preferably a bronze casting reinforced by flanges 4'! and 48. The lower end of the bronze casting which engages the square steel shaft is preferably formed in a V comprising the members 49 and llset at approximately right angles to each other so that they will engage the square sides of the shaft to which they are to be clamped.

The clamping member 5| comprises also a-V- shaped member having the sides 52 and 53 which likewise-may engagethe sides of the square steel shaft and comprising also flanges 54 and 55 through which bolts 56 and 51 may be threaded toengage the flange 58 and the flat portion 59 of the contact arm 46 in order to securely clamp the same to the contact shaft 45.

As will be noted especially in connection with Figures 2 and ass-en of the main contact arms 46 may be secured to the contact shaft45 so that rotation of the contact shaft 45 by the lever 35 will result in corresponding movement of the contact arms 46 for the purpose of opening or closing the circuit.

While any necessary number of contact carrying arms may be mounted upon the contact shaft as the specific circuit connections may require. only'one lever 35 is necessary for the opening and.-

closing operations which result in rotation of the shaft 45'and the operation of the various contacts.

"In. order to obtaina balanced structure it is preferred that the shaft 45 substantially at the center so that the "mechanism may be properly balanced.

Movable main contacts 46. The back of the contact arm 46 has a part-' cylindrical depression 6| and the front of each of the contact levers has a similar depression 62. A bronze pivot pin 63 is placed in these depressions. This pivot pin has flanges at each side and also a flange in the center between the two in the arm, there would be copper and brass bear- 6 lever 35 be secured to the contact levers 56 in order to prevent any lateral movement of the members with respect to each other.

.Each of the contact levers 56 is drilled at 64 so that a pin 65 may 'be inserted therein. The pin 55 is preferably of dumbbell shape and acts as an equalizing yoke between the two contacts 66-66. A link 56 engages the pin 65 between the two contact levers 56-66 and is extended up through a perforation 61 in the contact arm 46 into the recessed area 68 of said contact arm. A compression spring 69 forms the main contact spring and is retained in position between the base of the recess 66 and the spring cup ill which is held in place on the spring link 66 by the cotter I pin. ii.

The spring link 66 in extending between the two main contact levers 66 has an eye 56' which engages a groove 65' in the pin 65 in order to prevent its moving to either side.

When the main contacts are disengaged in the manner shown in Figure 4, the lower ends I2 of the main contact levers 56 press against the contact arm 46 in the manner shown.

For simplified assembly the only element which retains the pin 63 in place is the pressure of the spring 69 upon the main contact lever.

In the closed position the pressure through the contact lever 56 between the spring 69 (bearing ,on the pin 65) and the contact 4| serves to maintain the adequate pressure necessary to hold the pin 63 in place. In the open position, the pressure of the bottom end 72 of the main contact lever 56 against the contact arm 66 and the pull of the compression spring upon the pin 65 of the lever 66 using the member 12 as a fulcrum serves to maintain-the pin 63 in place.

This design of pivot provides long wearing surfaces. The spring link and pressure equalizing pin may be made of hard steel so that their area of engagement may be small. The area of engagement at the pin of the contact levers may be of relatively soft material.

I The pivot pin engaged by the half cylindrical surfaces of the contact arm and the contact,

levers provides a maximum of area for the softer parts. This area could not be obtained in the same width or pin length by any other method.

If the levers were formed to rock in a groove ing surfaces which are far inferior to the steel pin between them.

During the closing movement there is no instant when there is any relaxation of pressure upon the pin 63, for until the main moving contact tip 4| is brought into contact with the stationary contact tip 46, the bottom end 12 01. the contact lever- 66 engagesv the contact arm 46 in the manner shown in Flgure l.

Only after the moving contact tip 4| is in engagement with the stationary contact tip 46. is there a transfer ofthe fulcrum or the base of wardly extending flanges In seen in connection with position of Figure 3, there'is again washer 38. As-will be seen sufficient pressure to maintain the pin 83 in place.

During the opening maintained upon the pin 83 by reason of the fact '88 by its pressure on pin 88 forces contacts 48 and 4| against the rotation of the contact shaft 48, the end 12 of the contact lever presses against clamping portion 48 oi the contact arm 48, whereupon the base of pressure is transferred from contact tip 4| to end portion 12. In this manner, the spring pressure is always exerted to maintain pin 83 in position.

The rotation ofthe main contact lever 88 about the pin 82 during the closing operation necessarily results in a slight sliding motion of the movable contact tip 4| with respect to the stationary contact tip 48 so that a wiping action oc curs tending to clean the contacts.

As seen also in Figures 3 and 4, the back of the contact levers are drilled. and tapped for the securingscrews J3 in order to attach the flexible conductor S3 thereto.

The upper end of the flexible conductor 43 is slit so that separate screws 13 may attach the separate ends to the two separate contact membars 83 to allow independent movement or the contacts. Ihe arrangement of the lever arms above and below the contact pivot is such that movement, pressure is against a stop on the during heavy current flow the magnetic forces set up will tend to increase the pressure between the moving and stationary contacts when the flow of current is between the stationary contact tip 48 and the movable contact tip 4|.

By the use of two contact levers of this type for each pole of the circuit breaker, an adequate contact at each pole is ensured.

M 01711318 arcing contacts The arcing contacts 81 are mounted in the upper part of the contact arm 48, and are supported by arcing contact levers 75. The arcing contact levers H5 preferably are each cut from a bar oi extruded copper and in this case also I have found it preferable to use a pair of such contacts and levers for a single pole. Each of the arcing contact levers i5 is pivoted on the pin 78 which is grooved between the contacts to take a hair pin spring H which serves to keep the pin 18 in center position. A second pin 78 is mounted in the top of the contact arm 48 between two up- 18 thereof.

An appropriate bushing may be placed between the flanges so that the pin may be securely riveted over them without bending them. The eye 88 of the spring link at is placed over the bushing, the said spring link 8| extending beyond the back of the arcing contact levers l5.

Pins 82 having-rounded heads are driven into the upper part or the back of the arcing contact lever 18. p l

A spr ng cup 83 is pressed against these pins by the compression spring 84 which is held inmore particularly in Figure 18, the contacts 81 are held against turning or other displacements by the shoulder II which engages a corner of the arcing contact lever 18. The ends of the contact arm flanges bear against the outer sides of the two arcing contacts and the projection 82 of the spring link separates the two arcing contacts 8l81 from each other. thus serving adequately to position them.

As is seen in Figures 3, 4, the lower end 01' the arcing contact lever 78 is off-set at 88' to receive the and Ma flexible conductor 83. The conductor like the conductor 43 is also slit, the ends thereof being riveted at the ofl-set 33' to the arcing contact lever 15 by means or the rivet 84 passing through the washer plate 38.

The oifset 33' is curvedawayat 98 from the flexible conductor and the washer plate 35 is curved away at 91 therefrom for the purpose of preventing kinking during operation. This flexible conductor 93 is led down to the lower terminal block to which it is connected by the same screws 38 that hold the main contact lead 43.

The main contact levers, sitiun, are held against in contact open potheir iulcrums and arm by a compression spring at the back of the arm, acting on a link connected to the two contact levers between the fulcrum and the stop. The contact surface is at the top of the lever above the fulcrum. The

flexible conductor is secured to the bottom of the lever belowthe fulcrum.

When the shaft and arm are moved to contact closed position, the contact ends of the levers are rotated about their iulcrums and pushed back from their advanced position, moving the bottom stop clear of the arm. This compresses the spring and increases the contact pressure. The use of a single spring and link between the two levers permits the pin to act as an equalizing yoke.

place on'the link 8i by thespring cup 85 at the oppositeend which in turn is held in position by the cotter pin 88. The arcing contact 81 is mounted upon'the arcing contact lever IS-and is preferably formed or cut from an extruded copper bar and is provided with a contact race 88. preferably ofwElkonite silver which is'soldered to "thecopper. .Each of the contacts 8'! of each of the contact levers 15 is held in place upon its contact lever by a socket head cap screw 83 and lock The attachment low the fulcrum causes the magnetic forces to balance about the fulcrum so that. the contact pressure may remain the same or increase dur' ing fault current.

The auxiliary or moving arcing contacts are mounted at the top of the arm. n this-case the spring is above the fulcrum and below the detachable contact tips. Equalization of pressure is arranged in the same way. Maintained pressure during fault or inrush current is provided in the same manner.

Overcurrent coil connections It should also be noted that the flexible lead I 08 from the arcing horn hereinafter described is also connected to the terminal block 44. It will thus be seen that the three flexible conductors I08, 83 and 43 are all led from the contact structure to the lower terminal 44 to which all three are or maybe secured by the same screws and lock washers. The angle of the terminal and of the screw 98 a repair man may reach these screws over the back edge of the bracket shelf 38. The lower terminal or pigtail posts may have connected thereto a coil 8 which may energize an over-current magnet.

This coil may have a cross section of copper and the requisite number of turns corresponding to the current rating of the circuit breaker, one

terminal of the coil being connected to of the flexible conductor beis selectedrso that lower terminal post M and the opposite endof the coil being connected to the back connection stud III which has the securing block II2 welded to it at the face of the panel 23.

The back connection stud III is held inplace in the panel 23 by the screws H3 and III which pass through and engage the clip H5. The terminal post 44 is bolted in place on the panel 23 by means of the bolts IISand-lock washers III. In other words, therefore, the current is not led directly to the back connection stud ill but through the lower terminal post 44 and through the coil III] of the over-current magnet to the back connection stud III through which the connection is made to the circuit.

The coil III! of the over-current magnet is therefore connected in series with the contacts. It. might here be noted that the uppe back connection stud 42 is likewise connected through the panel 23 by means of screws H8 and H9 engaging and passing through the clip I20 and is therefore held in position in the same manner as the lower back connection stud HI.

When the circuit breaker therefore is closed,

the current flowing into the upper stud 42 enters the main contact block36, passes through'the main stationary contact surface 40 to the main movable contact surface 4| and into the main contact, lever 60 passing therefrom through the flexible lead 43 to the lower terminal block 43 around and through the coil IIB to the lower back connection stud II I and thence back to the circuit to which the same is connected.

The over-current coil I II] will thus be in series with the main contacts; and, after these are opened, with the arcing contacts; and,fina1ly, with the arcing horns; since the leads 3, 93 and IIIII each are connected. to the pigtail post The arcing contact circuit is in parallel with the circuit-through the main contact tips AI} and ll. The arcing contacts are designed to make before and separate after the main contacts during the closing and opening so that as is hereinbefore described, the arcparticularly during the opening may be made between the arcing contacts so that the main contacts which carry the load should not be roughened or distorted to offer any substantial resistance to the passage of current.

Blow out magnet and stationary arcing contact The current path from the arcing contact tip I 88 to the arcing contact lever I and through the'flexible lead 93 to the lower terminal block 44 has been described. The movable arcing contact tip 38 engages the stationary arcing contact tip I2I. Current is led to the stationary arcing, contact tip I2I in the following manner:

Current from the upper connection stud 42 flows into the lower terminal I25 of the blow out magnet coil I22 aroundthe coil to its upper ter minal I29 and thence to. the stationary arcin contact I23. From the stationary arcing contact, the current flows to the stationary arcing contact tip I2I-, thence to the movable arcing contact tip 38, thence through the arcing contact lever flexible lead 93, the terminal block M, the coil I'III a-nd the connection stud III in the manner hereinbefore described.

The arcing contacts, particularly the movable,

arcing tip fil -88, may readily be replaced after the same have become worn. When the circuit breaker is closed, the resistance of the circuit through the main contact 36 and 63 is low as circuit so that compared with a relatively small current flows through the latter.

The main stationary to the back connection stud as is the lower terminal of the blow-out magnet coil I22 by means of screws 38. Screws I19 passing through panel 23 serve to fasten the lower terminal of blow out magnet coil I22 and angle clip I23 to panel. Screws H8 in turn fasten back connection stud 42 to the angle clip I2II. The electrical connection between the back connection stud 42 and the lower terminal I25 of the blow out magnet coil I22 is made by direct contact between the angle clip I and the screwIIS as well as by the direct pressure of the terminal I against the connection stud 42.

The coil consists preferably of a strip of bar copper-wound in a helix, the lower end at I23 being sweated and pinned by pins I21 and I28 .to the lower coil terminal I25 and the upper end being secured to a flat plate terminal I23 which lies against the panel I23. that current flowing from the lower coil terminal to the upper coil terminal flows around the slotted cylindrical iron core I30 in a clockwise direction in the views of Figures 3 and 4.

A fiber tube I3I insulates the core I30 from the coil I22. Insulated side plates I32 are fastened on each side of the coil terminals. The arcing terminal I23 also out from an extruded brass bar is secured to the upper coil terminal I29 and the panel 23 by screws I33, threaded into the nut plate I34 which is further anchored in position to provide a secure attachment of the members by the screws I35, the heads of which are embedded in the recess I36 so that they may not interfere with the securement of the coil terminal I29 to the'panel.

The upper part I 38 of thearcing contact I23 is extended along the panel and forms a hook I33 for anchoring the arc chute in the manner hereinafter described. 4 I

The arcing contact I23 curves around theblow out coil as seen in Figures 3 and 4 and forms an arcing horn. The arcing contact is preferably wider than the coil I22 and as seen in Figures 3 and 4, its under surface rests against the edges of the insulating side plates I32. As has been above described, the arcing contact tip IN is at the lower end of the arcing contact I23 and is preferably a. contact surface of Elkonite silver.

As seen in Figure 2 the contact shaft 351s a square steel bar which as above described is covered with phenolic insulation molded in place.

Each end of this shaft is drilled at I-IOa to re-- ceive the bearings I40. Theshaft itself extends between the side plates 28 and 29. The bearings are brass cylinders inserted in holes in the side plates to which their drilled flanges MI are secured by screws I 32. Y

When the screws I 32 are removed and the two bearings at each end are withdrawn, the shaft and the entire contact assembly may be removed from between the side plates provided of course that the flexible leads have been disconnected and also provided that the connection between thelink 34 and the arm 35 of the contact shaft are separated.

Assemblyand operation of the contacts. The contact arms 46 are secured to the contact shaft by clamp members 5| which are held in place by a pair of screws ifiand 51 on each side of the shaft.

the resistance through the arcin contact 36 is attached i The coil is wound so These two springs may I its original position The outside poles are suitably positioned by the contact arm caps or clamps Ha while the middle pole arm is held in position by the cap As is seen more particularly in Figure 3 the clamp or cap 5| is extended to form the-shaft actuating arm 85 and is drilled to receive pin ill in the upper end or the main toggle link it. A movement of the operating mechanism M will raise or lower the pin I26, therefore raising or lowering the shaft actuating arm and so rotate the contact shaft to move the contacts into and/or out of engagement.

As is more clearly seen in Figure 2 secured to either or both ends of the steel contact shaft 45, is a steel arm 220 and 229. Each of these arms carries as will be noted, two studs 223 and 226 which are riveted in place.

Secured to one or the studs or each of the members 22c and 22E is a contact opening spring the lower end of which may be attached to studs riveted to the insides of the bracket side plates. bias the shaft towards opening position and assure quick opening.

The second of the studs for instance stud 223 on the arm 22d may be utilized to operate auxii iary switches or other devices by means, for instance, the vertical insulatedshaft 230 attached to this stud and passing through the shelf of the bracket 30 (Figure 2).

Thus, for instance, the vertical shaft 2353 may operate auxiliary switch 23 in any suitable manner for any suitable purpose. The rotation of the contact shaft 45 towards opening position will through the arm 228 and the stud 223 force the vertical link 2359 downwardly. link 230 is connected by pin 23i to the crank. 232 on the shaft 233 of the switch 23 3.1 The downward motion of the vertical link 2% will result in rotation of the crank 232 and will therefore result in the rotation of the shaft 233 and in the consequent operation of the various contacts and other portions of the switch suitably connected to and actuated by shaft 2%.

Such switch 234'; may be used where, for instance, the circuit breaker with automatic reclosing circuits when it is open and such relay will obviously be reset to closing mechanism hereinafter described rotates the contact shaft 45 towards closing position thus raising the insulated link 23!! and operating the switch.

As has been above pointed out, preferably three contact arms 46 are mounted on this shaft, one for each pole of the circuit breaker as seen in Figure 2. On each side of each arm, there is cemented to the shaft insulation a Bakelite washer I43 which improves the pole to pole and pole to ground insulation.

As will be noted in Figure 2, the inter-pole washers are bevelled and flanged so that the bevelled and flanged portions I thereof are spaced apart so that an inter-phase barrier I45 secured to the panel may extend between them. The cooperation of these parts makes it impossible for any flexible conductors of adjacent poles to be drawn together during heavy current flow while at the same time any possibility of arcing over is obviated.

In the construction and arrangement of the contacts, the movable main contact is supported by an'operating arm on the contact bar or shaft, 7 and is connected to the lower stud by a flexible shunt of suitable size.

on the main contact is obtained The verticalv is to be connected when the solenoid or manual 1 main contacts is such that the contact shaft 45 and through the use of a compression type coil spring,

mounted outside the current path, and, consequently, is unaffected by heating.

The pressure on the arcing contacts is also obtained by the same type of compression type coil spring protected from the arc.

The main contacts are protected by the sequence of operation in opening or closing of the device, since the main contacts close after th arcing contacts and open before them. I

Although with the construction herein described, replacement of the contacts should not be necessary, the arrangement of the movable main contact lever and the movable arcing contact is such that access to both stationary and movable parts with a minimum amount of labor is possible.

As hereinafter described, accessibility of the it is necessary only to remove one screw from the arc quencher assembly and lift it on manually so as to reach the contacts. In addition, as is hereinbeiore de scribed, the removal of the two bearings 546,01. the main contact shaft and pigtails is sufficient to make available all parts of the contact mecha nism for replacement, cleaning or repair.

The individual poles of the circuit breaker are each rigidly mounted on a rigid insulating shaft so as to insure the simultaneous opening and closing of all contacts. The use of a single trip free mechanism operating the main contact shaft also insures that all or the poles will operate simultaneously and precludes the possibility of opening individual poles without opening others.

An important feature of the present invention is that the same structure may be used for single pole or multi-pole operation, that is, seen for instance in the structure of Figure 2, the circuit breaker mechanism is so arranged that three poles are simultaneously operated by a single closing and tripping mechanism. The same type of structur may be so arranged as to take one, two or four poles or more.

Are chute, are home and blow out In the actual operation of the contact assemblies herein described, when the contacts are fully closed and the latches are then tripped, the contact arm 48 rotate in a counterclockwise direction in the views of Figures 3 and 4. As the arm and the contact pivot pins 16 and 63 move away from the stationary contacts, the springs 69 and maintain the moving contacts in engagement with the stationary contacts until in the rotation of the contact levers these levers 15 and 60 strike their respective stops.

During this movement, the lower end 12 of the contact lever 60 strikes the part of the contact arm 46 which surrounds the shaft 45. As this point in the movement, the main contacts separate while the arcing contacts are still engaged. It is thus seen that the circuit through the main contacts is interrupted and all the current is transferred to the circuit of the blow out coil I22 and the arcing contacts. The core I" therefore and its associated pole pieces are highly magnetized in proportion to the current flowing.

As seen in Figures 2, 3, 4 and 5 surrounding each pole is anparc chute I50 comprising side plates iii of fiber and supporting between them 3;: shorter parallel spaced plates I52 also'of The entire group is held together preferably .notch I15 in the 'thevariousother by rivets I53, I53 making-as far as'possible a rigid assembly. Preferably, the rivets comprise, as seen in Figure. 5, a central metal'tube-like arrangement I54 and an outer insulating cylinder I55.

As seen in Figures and 4, near the panel -I6l, and lock washer I65 to the bridge 31 of molded-insulating material. This metallic clip. I6I is electrically connected to the flexible conductor. I 00 which in turn connects it to the lower pigtail-terminal 44. At the end of the opening movement of the arcing contact the tip 01 of the movable arcing contact 15 moves under the sta tionary arcing horn I60 in the manner shown in Figure 4 so that the arc terminal is transferred to the stationary arcing horn I00 andthe current flows through the conductor I00 to the lower terminal block 44. The current is first transferred from the main contacts to the arcing contacts, and, when the arc is then transferred to the stationary arcing contact or horn I50, the movable arcing contact is shunted out of the circuit.

' 23, the inside plates I52 are separated by fiber As seen in Figure 2, the blow out core I30 extends beyond the sides of the blow out coil I22 a distance equal to the thickness of the fiber side I plates I5I.

The fiber side plates are notched at I15, as seen in Figure 1, so that they may embrace the core I30 while their edges rest against the panel 23. Byfthis arrangement, any possible impediment to the magnetic fluxes induced by the core in the pole pieces hereinafter described is obviated.

Ferrous blow out plates or Figures 1, 2, and 5, are surfaces of the side plates means of rivets or other suitable attaching means pole pieces I16, secured to the outer I'I1.. Theseblow out plates or pole pieces, as seen particularly in Figure 1, cover a party of the fiber plates I5I so that when the arc chutes are in position against the panel 23 and in proper relation to the contact assembly, the surface of each end of the core I30 is in contact with a corresponding iron blow out plate or pole piece I15.

Each of the side plates has its back edge I80 (Figure 1) bevelled on the inner side thereof so that it may he slid in position easily pastthe notches of the insulated bridge hereinafter described. I

'I'henotch I15 around the blow out core- I30 (Figure l) and the lip I39 on the stationary which engages the hook I51 of arcingcontact I23 thenber spacer I50 of the arc chute I50 (Figure 3), cooperate to position the back end of the arcchuteinexactrelationtothepanel 23 andto portions of the contact assem- Tbefrontendissim rtedandlockedinplace bymeansofthescrew I5I whichin turn is aiiixed by means of the I5I of the arc chute by I04 passingthrough the bridge "and through the angl clip.

screw I62 to the stationary arcing horn I50 which in turn is preferably an integral part of or securely attached to the arcing chute I50.

The front end of the arc chute is therefore securely positioned in place by means of the screws I50 and I62; It will be noted that removal of the screw I62 will permit the withdrawal of the entire arc chute from the contact assembly. That is, when the screw IE2 is no longer in engagement with the angle clip I6I then (Figure 3) when the entire arc chute I50 is slid towards the left, the hook I51 of the fiber spacer I55 may be disengaged by this simple horizontal movement from the hook I39 of the arcing contact I23 and as seen in Figure 1, the notch I15 of the outer plate I5I may by the same motion slide out of engagement with the blow out core I30. The are chute therefore is so arranged that a simple unscrewing of the screw I52 will permit removal thereof.

It should be noted that the screw IE2 is so arranged that it need not be completely removed but it may be rotated a sumcient number of turns to disengage it from the clip I6I and may remain in the portion I63 of the arcing horn I during removal of the arc chute. By this simplifled means involving rotation of a single screw, the arc chute may be securely mounted in place or quickly removed by a single motion in a horizontal direction. 1

Thearc splitting plates I52 (five "in number in the preferred embodiment) have, as seen in Figures 3 and 4, their lower edges shaped in two arcs I and I9I which are concave in a downward direction with the cusp I92 between them rounded. This cusp lies approximately midway between the stationary arcing horn -I23 and the front arcing horn I50. The downwardly extending cusps facilitate the entrance of the arc into the slots between the plates and are so arranged that a relatively small longitudinal length of the arc is first forced between the plates and so that as the arc is blown upwardly, progressively greater lengths of the are are forced between the plates. As is also seen edges of the middle one I52a being the highest and the outer plates I520 being the lowest, that is, extending downwardly a greater distance. The intermediate plates I52b are of a height so that the lower edges extend in planes substantially between the position of the edges of the middle and outer members.

As is also seen in Figures 3 and 4, the five plates here shown have perforations I95 of suitable size in Figures 3, 4 and 5, the lower and shape, spaced and arranged to permit the flow of'arc gases from the slot I96 (Figure 5) between one pair of plates to the slot between 7 another. In order to provide a more turbulent,

condition of the arc gases and in order to insure contact of the arc gases with the various plates, the holes or perforations I95 of each of the plates are. in staggered relation with respect'to those in adjacent plates.

Upon opening of the main contact-sand formation of the are between the arcing contacts 14' and I23, the arcis immediately transferred from the arcing tip I5 to the arcing horn I50.

The current flowing through the coil I22 energiaes the magnet comprising core I30 and ferrous plates I15. producing a flux across the arc space. This flux forces the' arc upwards towards and into the arc chute I50. Whenthe arc reaches the lower edges ofthe arc splitters or the plates I52 are of different heights,

" both at the top and the front.

plates I 52 it is squeezed or flattened to be forced between the two outer plates I520 and Inc. Further movement forces the are between the intermediate plates I52b-I52b further reducing its horizontal width.

As the arc is pushed further it may enter'one of the slots I96 or it may be divided longitudinally in two or more slots. In either case, the arc gases have an opportunity to expand through the holes I95 in the plates I 552.

This provision for permitting the arc gases to expand from slot to slot reduces the back pressure and hence permits the blow out magnet to force the arc upward at full speed.

The tendency of the ionized gases discharged from one slot to enter another through the parforations I95 permits parallel arcs to exist over sections of the arc. This causes greater instability and increased tendency to speed the extin=- gulshing of the arc.

By this means also a large cooling area provided which further contributes to shorten the arcing time. Preferably the arc gases are sufficiently cooled. and deionized by the arc quencher so that when, in the case of alternating current, the current passes through zero in the cycle immediately following the formation of the arc, the gases will be sufficiently deionized to provide an extremely diflicult path for an arc and thus prevent the re-striking thereof. The are therefore may be quenched within A of a second of the formation thereof.

Inter-phase barriers Sufficlent inter-phase barriers are provided by the side plates II of the arc chute. However. additional inter-phase barrier plates Mil (Figures 1-4 inclusive) may be used to make it im possible for any flashing over of the are from one pole to the other. These inter-phase bar riers are placed between the arc chutes and can ried up so that they are aligned with the top of the panel 23 and may be secured to the panel by suitable angle clips 2M, Figure 2, and screws I passing therethrough.

As will also be seen iii-Figure i, the interphase barrier I45 extends beyond the arc chute The front lower corner rests on the insulation bridge 3'! while as has been before pointed out, the back end bears against the panel and extends down between the shaft insulation disks Its-I63.

Lower interphase barriers IIIiIa (Figure l) are aligned with the upper interphase barriers and secured to the panel 23 by screws IIlla and Iiiia thus preventing any tendency of the flexible leads to approach each other or any current at that point from arcing over.

The lower back corner of the upper interphase barrier is supported by a strip of insulating material secured to the panel Just above the top of the housing brackets. The lower interphase barriers align with the upper ones and are secured to the panel by screws threaded into their edge. These lower'barriers are notched to surround the shaft. They prevent the flexible conducto'rs from being drawn together during fault current. I

General operation and arrangement III) to permit the breaker above its trip setting for The specific details of the are not herein discussed no part of the present inthe over-current coil to carry normal load. short periods of time. time delay elements since they constitute vention.

The various elements of the circuit breaker and the operation of each of the elements have been described in connection with the description of the members thereof. Each of the individual elements of the circuit breaker is in the present invention integrated with each of the other elements to form a unified integral operative whole.

The arcing contacts meet before the main contacts are in engagement with each other. Rotating the manual operating lever in the opposite direction trips the toggles in a manner hereinbefore described, and causes the contacts to separate, the arcing contacts separating after the main contacts and the are being established between the arcing contacts only.

The arc immediately thereafter is transferred to the arcing horns, and swept up by the magnetic blow out into the arc quencher I59.

The closing solenoid 53h may be utilized instead of the manual operating lever to close the circuit breaker and automatic tripping may be substituted for tripping by the manual lever by the use of the over-current coll i Id.

Fne over-current coil IIO responds to currents in excess of predetermined values passing through the circuit breaker and may be adjusted and calibrated for the particular rating of the transformer. AL

The arrangementof all of the parts of the cincuit breaker is such that assembly thereof is extremely simple. The entire arc quencher its ineluding the arcing horn ltd may be removed from the circuit breaker assembly by a single movement after the rotation of a single screw tea.

The arcing contact born I 23 is secured over the magneticblow out coil by readily disengagestance. as seen in Figure 2, a suitable time delay I I element I50 may be provided in connection with able screws and bolts I33. The blow out coil itself is readily removable by the removal of a single .set of screws H9. Even the stationary main contact is itself readily removable by rotation of the screws 38.

Assembly replacement and repair are thus greatly facilitated. Separation of the various parts for any purpose whatever is made easy and simple and the general arrangement of the members on the panel 23 facilitates the mounting of this panel in a switch board with other similar circuit breakers or other switch devices.

In the foregoing I have described only those parts of the circuit breaker necessary to fully understand the stationary contact structures including the structure and operation of the. main stationary contact, the blow-out coll, the stationary arcing contact and the arcing horn, and the various elements of each of these members which cooperate in supporting them upon their panel and which likewise cooperate in support ing additional structures, such as the arc extinguisher.

The various constructions herein described may be modified in mam; ways which will now be obvious to those skilled in. the art.

Accordingly, I prefer to be. bound, not by the specific disclosures herein but only by the appended claims.

This application is filed simultaneously with the application of Frank J. Pokomy, for Circuit breaker operating mechanismseflal No. 339,882,

the application of Frank J. Pokorny for Are quencher, Serial No. 339,783, the application of William Maxwell Scott, Jr., for Circuit breaker, Serial No. 339,687, and the application of William Maxwell Scott, Jr., for Circuit breakermovable contacts, Serial No. 339,689.

I claim:

1. In a circuit breaker mounted on a panel, a stationary contact structure comprising a back connection stud mounted in the panel and extending beyond either surface thereof means on the extension of the stud beyond'the rear panel surface for making electrical connection thereto, means onthe extension of the stud beyond the front panel surface for mounting a stationary contact thereon, a blow-out coil having a terminal block, said terminal block being secured to the front extension of the connection stud and additional means for supporting said terminal block on the panel, said additional means comprising a bolt in the panel connected at the front to said terminal block and at the back of the panel to a member connected to the back extension of the connection stud.

2. A stationary arcing contact structure com! prising a curved metallic member, an arcing contact at one end of the curve and an extension at the other end of the curve, and means cooperative with said extension for connecting said arcing contact structure to a terminal of the current supply and for supporting said arcing contact structure upon a panel, said means comprising screw threaded means passing through ill said extension and said panel and releasable from the front of said panel; a back connection stud; and a magnetic blow out coil one terminal.

of which is connected to said extension, and the other terminal of which is connected to said back connection stud, and a hook on said extension for positioning an arc extinguisher.

3. In a circuit interrupter, a panel of insulating material, a perforation in said panel, a back connection studof uniform cross section extending through said perforation, a conducting coil having a terminal engaging the face of said panel and said stud, releasable means maintaining said stud and said terminal in current carrying engagement, a member engaging the back of said panel and secured to said stud and screw threaded means for clamping said terminal and said member to said panel.

4. In a circuit interrupter, a panel of insulating material, a perforation in said panel, a back connection stud of uniform cross section extending through said perforation, a conducting coil having a terminal engaging the face of said panel and saidstud, releasable means maintaining said stud and said terminal in current carrying engagement, a member enga i the back of said panel and secured to said stud and screwthreaded means for clamping saidterminal and said member to said panel; a movable main contact and a stationary main contact maintained in current carrying contact with said stud by said releasable means. 7 g

5. In a circuit interrupter, a panel of insulating material, a perforation in said panel. a back connection stud of \mifo'rm and substantially rec-' tangular cross section extending through said perforation, a conducting coil having a terminal ensurin the face of said panel and said stud,

8 2,311,701 releasable means maintaining said stud and said terminal in current carrying. engagement a member engaging the back of said panel and secured to said stud and screw threaded means for clamping said terminal and said member to said panel; a movable main contact and a stationary main contact maintained in current carrying contact with said stud by said releasable means, said stationary main contact having a flat surfaceengaging the face of said panel.

6. In a circuit interrupter, a panel of insulating material, a perforation in said panel, a back connection stud of uniform and substantially rectangular cross section extending through said perforation, a conducting coil havin a terminal engaging the face of said panel and said stud, releasable means maintaining said stud and said terminal in current carrying engagement, a

member engaging the back of said panel and secured to said stud and screw threaded means for clamping said terminal and said member to said panel; said coil having a second terminal comprising a fiat plate positioned against the face of said panel, an arcing horn partially surrounding said coil and having a flat face engaging said second coil terminal and screw threaded means operable solely from the face of said panel for maintaining said arcing horn and said second terminal in current carrying engagement and .securing them to said panel.

:7. In a'circuit interrupter, a panel of insulating material, a perforation in said panel, a back connection stud of uniform and substantially rectangular cross section extending through said perforation, a conducting coil having a terminal engaging the face of said panel and said stud, releasable means maintaining said stud and said terminal in current carrying engagement, a member engaging the back of said panel and secured to said stud and screw threaded means 'for clamping said terminal and said member to said panel; said coil having a second terminal comprising a flat plate positioned against the face-of said panel, an arcing horn partially surrounding said coil and having a flat face engag- 1118 said second coil terminal and screw threaded means operable solely from the face of said panel for maintaining said arcing horn and said second terminal in current carrying engagement and securing them to said panel; and a movable arcing contact and a stationary arcing contactmounted on said arcing horn, said coil being in circuit between said stationary arcing contact and said stud. 4

. 8. In a circuit interrupter, a panel ofinsulat ingmaterial, a movable contact and a stationary contact, means for actuating-said movable contact into and out of e agement with said stationary contact and for maintaining current carrying pressure therebetween, a back connection stud of uniform rectangular cross section I throughout its length extending through said panel, said stationary contact comprising a con-' tact face of low resistance contact material and a contact block formed to engage the. end and one face of said stud and having a surface engaging said panel to oppose the current carrying pressure between said contacts and releasable mns'for securing said contact block to-said 

